1. Field of the Invention
The present invention relates to a ceramic capacitor of a surface-mount type, which is particularly suitable for use in a medium to high tension circuit, such as a horizontal resonance circuit, an AC noise suppression circuit or a rectifier circuit, of a general electronic device or a power supply.
2. Description of the Related Art
In recent years, with the progress of downsizing of electronic circuits used in an electronic device or a power supply, a demand for a ceramic capacitor of a type which can be assembled by the surface-mount technology on an electronic circuit has increased because many ceramic capacitors are used in the electronic circuit. The ceramic capacitor of this type is hereinafter referred to as "surface-mount type ceramic capacitor".
An example of conventional surface-mount type ceramic capacitors will be described with reference to FIG. 5 of the accompanying drawings.
As shown in FIG. 5, the conventional surface-mount type ceramic capacitor includes a dielectric ceramic substrate 1 made of a dielectric material such as ceramic, a pair of electrodes 2 made of a conductive metal such as silver and disposed on upper and lower surfaces of the dielectric ceramic substrate 1, a pair of lead terminals 3 connected to the electrodes 2, respectively, by means of a solder or a conductive adhesive, and a cover member 4 made from an insulating synthetic resin (hereinafter referred to as "insulating resin") and containing the dielectric ceramic substrate 1, electrodes 2 and an inner part of each lead terminal 3. Each of the lead terminals 3 has an intermediate bent over a side surface la of the dielectric ceramic substrate 1, and a generally hook-shaped external terminal portion 3a extending laterally outwardly from a front end of the intermediate portion to the outside of the cover member 4 and bent over an outer surface of the cover member 4. More specifically, the external terminal portion 3a extends from one of opposite side surfaces 4a to a bottom surface 3a of the cover member 4.
With this construction, however, since the lead terminals 3 are held in direct contact with the side surface 1a of the dielectric ceramic substrate 1, it occurs likely that when the ceramic capacitor is used in a high tension circuit, a spark or a short takes place between the lead terminals 3 and the dielectric ceramic substrate 1 due to electric lines of force concentrated on the lead terminals 3. In addition, since contact surfaces between the lead terminals 3 and the dielectric ceramic substrate 1 are not filled with the material (insulating resin) of the cover member 4, when the ceramic capacitor is subjected to a high temperature, the cover member 4 tends to crack due to the difference in the thermal expansion coefficient between the dielectric ceramic substrate 1 and the cover member 4. Furthermore, residual gases when existing between the dielectric ceramic substrate 1 and the lead terminals 3 will exert negative effects on the results of a heat cycle test and the heat-resisting property of the ceramic capacitor.